This application claims the benefit of Korean Application No. 57556/1997, filed Nov. 1, 1997, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method and apparatus for recording and reproducing data on and from an optical information recording medium, and in particular, to a method and apparatus for recording and reproducing data by irradiating a light beam to an optical disk having a wavelength characteristic curve relationship (response to light beams of different wavelengths).
2. Description of the Related Art
An optical disk, which is one of different types of optical information recording media, has widely been used to record and reproduce various information including audio and video data. According to the number of times information is recorded on the optical disk, the optical disk is classified as a read-only type disk, a recordable or write-once type disk, a rewritable or overwritable type disk, etc. The read-only type disk cannot write data but can read data. Examples of the read-only type disk are a digital audio compact disk (CDDA), a read only memory compact disk (CD-ROM), and a digital video disk (DVD)-video, which are commercially available. As examples of the recordable or write-once type disk which can write data only once, there are a recordable compact disk (CD-R) which is commercially available and a recordable digital video disk (DVD-R) which is expected to come onto the market. The rewritable or overwritable type disk can write data several times using an magneto-optical or phase-change method. As examples of such a type of optical disk, a rewritable compact disk (CD-RW) and a power disk (PD) are commercially available, and a random access memory compact disk (DVD-RAM) is expected to come onto the market.
Data is recorded and reproduced on and from the optical disk by irradiating a light beam. A laser beam is used as light, and a semiconductor laser such as a laser diode is used as a light source for generating the laser beam. To record data on the optical disk, an optical output of the light source should be approximately several tens of mW, in consideration of the optical efficiency of an optical pickup. The higher the optical output is, the faster a recording speed is. However, the light source having the optical output higher than such several tens of mW is expensive and generates heat due to a loss of light. Therefore, there is an upper limit of the output of the light source in use.
The CD-R and CD-RW of a CD series are standardized to use the light source having a wavelength of 780 nm, which is an infrared wavelength band. Meanwhile, the DVD-ROM, DVD-R and DVD-RAM of a DVD series are standardized to use the light source having a wavelength of 635-650 nm, which is a red wavelength band. Among theses disks, the CD-R and DVD-R have a wavelength characteristic curve relationship (response). This means that the CD-R and DVD-R have particular reflectance-absorption values based upon the wavelengths of the light beams irradiated thereon. Since the material of a recording layer of the CD-R or DVD-R contains a coloring matter, the absorption rate differs according to the waveform band and the reflectance of the disk varies. The characteristic of the reflectance as a function of the wavelength of the CD-R is illustrated in FIG. 1. As shown in FIG. 1, the recording layer of the CD-R is formed such that the reflectance at the wavelength of 780 nm is 70% or more, and the reflectance at the wavelength of 650 nm is 10% or less.
In the CD standard, since the rotating speed of the disk during recording and reproducing is low (about 1.2 m/s), it takes a long time to record and reproduce a large amount of data. This speed problem can be overcome by rotating the disk at high speed during recording. Thus, in a CD-R drive, the speed problem has been solved by rotating the disk at high speed, and the CD-R drive which can record and reproduce 2 or 4 times a reference speed of the CD has been announced. However, as the recording speed increases, the optical output needed to record data, that is, a recording optical power, increases as shown in FIG. 2, although it varies according to the sensitivity of the recording layer of the disk. The CD-R drive which can record and reproduce data on and from the CD-R uses a high output semiconductor laser having the wavelength of 780 nm. When recording data, the CD-R drive uses the semiconductor laser to produce a high output, and when reproducing data, it uses the semiconductor laser to generate a low output. As noted above, since the optical output needed to record data increases as the recording speed becomes faster, a high output semiconductor laser is required for high speed recording as opposed to the type of semiconductor laser required for low speed recording. However, since the high output semiconductor laser raises the cost of the drive and generates heat, its performance may be degraded.
As described previously, since the optical disk such as the CD-R having the wavelength characteristic curve relationship is used to record and reproduce data at the wavelength of 780 nm of a high reflectance, there is no problem in recording and reproducing data in the CD-R drive using the wavelength of 780 nm. However, if the recording optical power increases by speeding up the rotating speed in order to shorten the recording time, there are problems such as the generation of heat and a rise in cost. That is, in the CD-R driver using a single wavelength of 780 mn, there is a limit to the improvement of the recording speed.
It is an object of the present invention to provide a recording/reproducing method and apparatus which can efficiently improve a recording speed for an optical disk having a wavelength characteristic curve relationship.
It is another object of the present invention to provide a recording/reproducing method and apparatus which can improve a recording speed for an optical disk having a wavelength characteristic curve relationship which generates less heat and without raising the cost thereof.
It is still another object of the present invention to provide a recording/reproducing method and apparatus which can record and reproduce data in a CD-R at high speed and also can be applied to a drive using a rewritable optical disk of a DVD series. The present invention can also be applied to a drive for recording and reproducing optical disks having the same wavelength characteristic as the CD-R, and to the DVD-R, CD-RW, DD and DVD-RAM.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing objects and advantages of the present invention are achieved by providing an apparatus which enables data to be recorded on an optical disk exhibiting a difference in an optical absorption rate between wavelengths using a light beam having a wavelength of a first standard. The data recorded on the optical disk is reproduced by a light beam having a wavelength of a second standard. Preferably, the wavelength of the first standard is shorter than the wavelength of the second standard. For example, the wavelength of the first standard is 650 nm and the wavelength of the second standard is 780 nm.
The above and other objects of the present invention may also be achieved by an apparatus for recording and reproducing data on and from an optical disk exhibiting a difference in an optical absorption rate between wavelengths and which includes a first light source to generate light having a wavelength of a first standard of a high absorption rate in the optical disk; a second light source to generate light having a wavelength of a second standard of a low absorption rate in the optical disk; an optical system to convert the lights generated from the first and second light sources into beams to be irradiated to the optical disk and condensing light reflected from the optical disk; an optical detector to detect reflected light condensed by the optical system and to convert the detected light into an electric signal; a recording processor to drive the first light source by recording data according to the second standard, and to drive the second light source when reproducing data from the optical disk; a reproducing processor to reproduce data by the electric signal generated from the optical detector according to the second standard; and a controller to record data on the optical disk by driving the first light source by the recording processor, and to reproduce data from the optical disk by driving the second light source by the recording processor.
The above and other objects of the present invention are further achieved by a method of recording and reproducing data by irradiating a light beam to at least one of a first optical disk of one kind exhibiting a difference in an optical absorption rate between wavelengths and a second optical disk of another kind, and which includes the steps of recording data on the first optical disk by a light beam having a wavelength of a first standard of a high absorption rate in the first optical disk, and reproducing the data recorded on the first optical disk by a light beam having a wavelength of a second standard of a low absorption rate in the first optical disk; and recording data on the second optical disk by the light beam having a wavelength of the first standard, and reproducing the data recorded on the second optical disk by the light beam having a wavelength of the first standard. The first optical disk may be a CD-R and the second optical disk may be a rewritable disk of a DVD series.
The above and other objects of the present invention are still further achieved by an apparatus for recording and reproducing data by irradiating a light beam to at least one of a first optical disk of one kind exhibiting a difference in an optical absorption rate between wavelengths and a second optical disk of another kind, and which includes a first light source to generate light having a wavelength of a first standard of a high absorption rate in the first optical disk; a second light source to generate light having a wavelength of a second standard of a low absorption rate in the first optical disk; an optical system to convert the lights generated from the first and second light sources into beams to be irradiated to a currently mounted optical disk out of the first and second optical disks and condensing light reflected from the currently mounted optical disk; an optical detector to detect reflected light condensed by the optical system and converting the detected light into an electric signal; a first recording processor to drive the first light source by recording data according to the second standard, to drive the second light source when reproducing data from the first optical disk; a second recording processor to drive the first light source by recording data according to the first standard, to drive the first light source when reproducing data from the second optical disk; a first reproducing processor to reproduce data by the electric signal generated from the optical detector according to the second standard; a second reproducing processor to reproduce data by the electric signal generated from the optical detector according to the first standard; and a controller to record data on the first optical disk by driving the first light source by the first recording processor, and to reproduce data from the first optical disk by driving the second light source using the first recording processor and simultaneously operating the first reproducing processor, and to record data on the second optical disk by driving the first light source by the second recording processor, and to reproduce data from the second optical disk by driving the first light source using the second recording processor and simultaneously operating the second reproducing processor.